Colorado’s decision not to trade 38-year-old closer Rafael Betancourt may be a costly one, as he left last night’s game with an elbow injury.

Troy Renck of the Denver Postspeculates that it’s a serious injury–and specifically a torn ulnar collateral ligament–because “several teammates quietly patted him on the back” and “the gravity of the moment was powerful.”

He’ll undergo further testing, but a torn UCL would require Tommy John surgery and knock Betancourt out for most or perhaps all of next season. And at age 38 that might end his career.

Betancourt’s contract includes a $4.25 million mutual option for 2014, which the Rockies likely would have exercised. If he’s hurt they’ll no doubt decline the option, paying him a $250,000 buyout.